[I love Lucy]

I just was looking at this website pupepalace..and I was wondering why some newborn yorkies have white on the chests? What does that mean? Some other websites advertise large white chests as parti carriers, I understand why they would have the white chests but how about these standard yorkies??? Also I talked to a well known breeder and she was mentioning one of her pups had the little white on her chest and she wished that the other one she was keeping had the white on her chest too...? Does that mean better genes or better coat or coloring??
Thanks !